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Frag Tank, Sunlight, PAR meter usage

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richiev

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I have a series of related questions on a frag tank and PAR. In the never ending cascade of tanks, I ended up turning the 10 gallon QT tank I have into a frag tank. It is just a simple 10 gallon, with the ugly ass black trim and awful silicone lines that are constantly driving me insane. However, it holds water, and is shallow enough that the PAR is great with this AI prime I have on it.

First, major major major props to @H2OPlayar who loaded me up with frags yesterday. I'll do a tank tour and photo shot later, but here's a quick view (ignore the fake plant, it's a relic of something I was doing earlier, and it's hiding some equipment at the moment until I pick all the snails off it):



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FragTank2.jpeg


The questions I have are regarding lighting. I have a PAR meter which I got from a friend. It's a Apogee MQ-510. Over this tank I have an AI Prime.

When I'm measuring PAR near the center of the tank, under the light, at about the heigh of that orange monti cap, I'm getting ~225 PAR with these settings:

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I actually wasn't expecting PAR numbers that high, but I'm happy with them. So first question, does 250 PAR ~7in below the water surface seem reasonable for an AI Prime? I just want to triple check I'm not somehow using this completely wrong.

Second, I just had an obvious realization. This is sitting to the side of my WFH desk, which is right next to a window. I just realized that I can open the blinds and let a steady stream of light in, right onto the tank. In deciding if I want to do this, and deal with the bit of computer glare it gives, I took the PAR meter out. In the sunlight, at that same spot, my PAR is jumping from ~250 to 500-600+, is that real? I know the sun is bright, obviously, but I didn't expect a jump that big, and it seems like obviously great if I can get free energy for a couple hours of the day.

I know the concerns about temp swings from sunlight, but during winter this room is pretty cold and the heater is running pretty constantly. Also, I know the spectrum isn't what we consider ideal for coloration and can introduce algae, but in this tank I'm mostly looking for growth and it's pretty low nutrient so I was thinking it wouldn't be a big risk. Last question, is anyone successfully (or unsuccessfully) using sunlight to provide extra light to their frag tank? Anything to suggest on the topic?
 
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When I was running an AI Prime 16HD over my IM Nuvo 20, with the light mounted ~11" over the water's surface, I ran the Saxby presets about ~60% of max and was getting 250-300 PAR a couple inches below the water's surface. Light in the 'shaded' areas on either end of the tank at that height was about 150-170-ish PAR. I'm not sure of your light mounting height, but ~250 PAR at that depth is at least plausible to me with those settings.

As for whether it's real - the PAR meter is measuring it, so it's 'real' in the sense it's measuring more of the wavelengths the PAR meter checks. I don't know what the biological ramifications of that are, though. I'd probably suggest just keeping a close eye on your coral (particularly those that are more exposed to the increased light) and make sure they're continuing to do well as time goes on.
 
This video should walk you through what to expect for par from the Ai Prime:

As for the sun, 5-600 seems high but hard to tell. Take it outside in straight sunlight and see what it reads.

Using sunlight to light your reef can obviously be done (you know, nature and all) but in an aquarium it frequently leads to algae.
 
I kept my QT tank in sunlight - the algae growing on the glass actually zero'd nutrients, which was nice in that QT scenario.

I remember this 400 gal sunlight tank
- Looks really nice and natural, but the corals look a little brown.
 
Well direct sunlight at noon will easily eclipse 1000 PAR, so 500-600 through a window doesn't really sound that obnoxious at all.

Temperature is a major concern with sunlit reefs though especially if the tank is small. If you have something like an Apex you may want to record some temperature data over the course of a day and see what happens. Way back when I had a sunlit soft reef and at times it did get up to 90F the corals told me they were hot too, so evaporation is probably a must to keep temps under control.
 
The PAR numbers you are getting sound in the right ballpark. Sunlight with only a few inches of water between it and the coral will give really high numbers; a few feet down it starts dropping off to more like what we light our tanks with generally. Also a few feet down the longer wavelengths are getting absorbed first giving the light spectrum and look we are more used to.

As far as the algae question, as far as I know it isn’t any more of a concern than otherwise lighting your tank very brightly. Sunlight is full spectrum so your corals won’t look as nice and you‘ll have more heat energy deposited you’ll have to watch out for. Plus the sun in our area is a lot more variable over the days and over the year than it is over the ocean at the equator, so it may be hard on your corals to constantly be adjusting.
 
sfsuphysics said:
Well direct sunlight at noon will easily eclipse 1000 PAR, so 500-600 through a window doesn't really sound that obnoxious at all.

Temperature is a major concern with sunlit reefs though especially if the tank is small. If you have something like an Apex you may want to record some temperature data over the course of a day and see what happens. Way back when I had a sunlit soft reef and at times it did get up to 90F the corals told me they were hot too, so evaporation is probably a must to keep temps under control.
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I do have a reef-pi running on this, which I was going to watch to see what happens. Today it had no noticeable effect, but I did decide to partially close the blinds just to avoid suddenly hitting new frags with 800 PAR for a short period.
Having paid attention to the sunlight today, with the blinds partially open, it seems like in reality this is just an increase for a couple hours a day due to surrounding shading outside. I'll have to keep track of things tomorrow, but my guess is most of the lighting is indirect at best, except for a couple hours in the late afternoon. Since I have the PAR meter I'll just take some periodic measurements just to know, but it's definitely not going to be a free 10 hours of 800 PAR :).

The biggest issue with sunlight is consistency. The key to success with coral is consistency.
Click to expand...

That's a fair point. It'd be an interesting study to see if consistency with lower PAR is > lesser consistency for a couple hours a day and more PAR.

I remember this 400 gal sunlight tank
Click to expand...

oof, I wasn't ready for that emotional kick in a reef video. Definitely brown. I wonder if just going hard on the rest of the spectrum with some lighting would help offset that. Eg just run only UV -> Royal Blue and let the sun handle the rest.
 
richiev said:
I do have a reef-pi running on this, which I was going to watch to see what happens. Today it had no noticeable effect, but I did decide to partially close the blinds just to avoid suddenly hitting new frags with 800 PAR for a short period.
Having paid attention to the sunlight today, with the blinds partially open, it seems like in reality this is just an increase for a couple hours a day due to surrounding shading outside. I'll have to keep track of things tomorrow, but my guess is most of the lighting is indirect at best, except for a couple hours in the late afternoon. Since I have the PAR meter I'll just take some periodic measurements just to know, but it's definitely not going to be a free 10 hours of 800 PAR :).



That's a fair point. It'd be an interesting study to see if consistency with lower PAR is > lesser consistency for a couple hours a day and more PAR.



oof, I wasn't ready for that emotional kick in a reef video. Definitely brown. I wonder if just going hard on the rest of the spectrum with some lighting would help offset that. Eg just run only UV -> Royal Blue and let the sun handle the rest.
Click to expand...
Sorry, I forgot about that part of the video when I posted it. Definitely tragic.
 
richiev said:
I do have a reef-pi running on this, which I was going to watch to see what happens. Today it had no noticeable effect, but I did decide to partially close the blinds just to avoid suddenly hitting new frags with 800 PAR for a short period.
Having paid attention to the sunlight today, with the blinds partially open, it seems like in reality this is just an increase for a couple hours a day due to surrounding shading outside. I'll have to keep track of things tomorrow, but my guess is most of the lighting is indirect at best, except for a couple hours in the late afternoon. Since I have the PAR meter I'll just take some periodic measurements just to know, but it's definitely not going to be a free 10 hours of 800 PAR :).



That's a fair point. It'd be an interesting study to see if consistency with lower PAR is > lesser consistency for a couple hours a day and more PAR.



oof, I wasn't ready for that emotional kick in a reef video. Definitely brown. I wonder if just going hard on the rest of the spectrum with some lighting would help offset that. Eg just run only UV -> Royal Blue and let the sun handle the rest.
Click to expand...
Re. consistency - Than of Tidal gardens (coral farmer) used to grow with some natural light in a greenhouse - some of his corals would suffer from the winter-summer variances.
 
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